JP2011044411A - Luminous flux control member, light emitting device, planar light source device, and display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a luminous flux control member capable of preventing occurrence of unevenness of luminance uniformity caused by leg-portion adhesion, to provide a light emitting device, to provide a planar light source device, and to provide a display device. <P>SOLUTION: The luminous flux control member 100 is provided with a flange part 140 of a nearly circular shape protruding toward an outer side in a radial direction of a third emitting face 110c of a light control emitting face 110 and a leg part 150 of a rod shape arranged on a rear face 120 and moreover in a region of an area width L on a reference optical axis side from a boundary between the flange part 140 and the third emitting face 110c. The area width L is expressed by the following expression: L=t×tan(α-β), provided that t: a thickness of the flange part 140 or a height of the outer most edge part 110d from the rear face 120, α: an incident angle to the light control emitting face 110 of light 113 parallel to the reference optical axis in the outermost edge part 110d, and β: an emitting angle of the refracted light 115 from a light control emitting face 110 created when the light 113 parallel to the reference optical axis is made incident to the light control emitting face 110 from the outermost edge part 110d. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a light flux controlling member, a light emitting device, a surface light source device, and a display device, and, for example, a light flux used as various illuminations such as a backlight light source that illuminates in a planar shape from the back side of a liquid crystal display panel and indoor general illumination. The present invention relates to a control member, a light emitting device, a surface light source device used for various types of illumination, and a display device that uses the surface light source device in combination with an illuminated member as illumination means.

  2. Description of the Related Art Conventionally, a surface light source device using a plurality of light emitting diodes (LEDs) as point light sources is known as illumination means for a liquid crystal display monitor used in personal computers, televisions, and the like.

  In the surface light source device, a plurality of LEDs are arranged in a matrix on the back side of a plate-like diffusing member having substantially the same shape as the liquid crystal display panel of the liquid crystal display monitor. The surface light source device causes light from the LED to enter the inside of the diffusing member from the back surface side of the diffusing member, and emits light that has entered the inside of the diffusing member from an output surface facing the back surface of the diffusing member. The liquid crystal display panel can be illuminated in a planar shape from the back side by the emitted light.

  There is known a light-emitting device that combines a lens body with this LED and controls the emission direction of light from the LED through the lens body. In such a light emitting device, a configuration for aligning the lens body with the LED is required.

  Patent Document 1 describes a lens body including a lens portion and an alignment portion made of an elastic material that aligns the lens portion with an LED. The alignment portion is formed with a fitting portion with the LED substrate. The lens body described in Patent Document 1 uses an elastic material for the alignment portion, so that the lens portion and the alignment portion are integrally formed of a PMMA (polymethyl methacrylate) material or the like. The lens body breaks down due to stress concentration on the lens, and the lens body is easily manufactured and aligned.

  Patent Document 2 discloses a light emitting device that controls the emission direction of light from a light emitting element (LED) via a light flux control member. This Patent Document 2 does not mention a method for fixing the light flux controlling member to the LED substrate.

  FIG. 1 is a plan view of a surface light source device constituting a conventional display device disclosed in Patent Document 2, in which an illuminated member such as a liquid crystal display panel is removed. FIG. 2 is a cross-sectional view of the display device, taken along line X1-X1 in FIG.

  As shown in FIG. 1, the surface light source device 1 is disposed on the back surface of an illuminated member such as a liquid crystal display panel, and has a plate-like light diffusing member 2 having substantially the same shape as the illuminated member, and the back surface of the light diffusing member 2. A plurality of light emitting elements 3 serving as point light sources arranged on the side at substantially equal pitches P, and a light flux controlling member 4 that controls emission of light from the light emitting elements 3 are provided.

  The light emitting element 3 and the light flux controlling member 4 constitute a light emitting device 5.

  As shown in FIG. 2, the display device 6 includes a surface light source device 1 and a member 7 to be illuminated that is disposed on the light emission surface 8 (surface opposite to the back surface 9) side of the light diffusing member 2.

  The light diffusing member 2 is formed into a sheet shape or a flat plate shape using a resin material such as PMMA (polymethyl methacrylate) or PC (polycarbonate) having excellent light transmittance. The light diffusing member 2 is formed in substantially the same size as the planar shape of a member to be illuminated such as a liquid crystal display panel, an advertisement display panel, or a sign display panel.

  The light diffusing member 2 has fine irregularities (prism-like projections, irregularities formed by diffusion treatment by embossing or bead coating) on the surface, or a diffusing material is mixed inside.

  The light diffusing member 2 diffuses the light emitted from the light control emitting surface 11 of the light flux controlling member 4 while transmitting it, and makes the light irradiated to the illuminated member uniform.

  The light emitting element 3 is, for example, an LED. The light emitting elements 3 are arranged in a matrix on the back side of the light diffusing member 2.

  The light flux controlling member 4 is a diffusion lens that controls the emission of light from the light emitting element 3, and is, for example, an aspheric lens. The light flux controlling member 4 is made of, for example, a transparent resin material such as PMMA (polymethyl methacrylate), PC (polycarbonate), EP (epoxy resin), or transparent glass.

  The light flux controlling member 4 includes a light control emitting surface 11 having a substantially circular planar shape for controlling light emission from the light emitting element 3, and main light including light emitted from the light emitting element 3 in the reference optical axis direction. A recess 13 for allowing the light beam to enter the inside, and a back surface 12 extending in the radial direction from the opening edge of the recess 13 and allowing the sub-light beam emitted from the light emitting element 3 to enter the interior at a large angle with respect to the reference optical axis; A substantially annular flange upper surface 14a protruding outward in the radial direction of the light control exit surface 11, a flange side surface 14b connecting the outer edge of the flange upper surface 14a and the outer edge of the back surface 12, and a luminous flux And a round bar-like leg portion 15 attached in a state where the control member 4 is positioned on the substrate 17. A portion surrounded by a back surface 12, a collar upper surface 14a, a collar side surface 14b, and a virtual surface (an inner peripheral surface of the collar 14) passing through the inner edge of the collar upper surface 14a and orthogonal to the rear surface 12 14 and the collar part 14 area | region of the back surface 12 is made into the collar part lower surface 14c.

  The light control emission surface 11 protrudes upward (to the light diffusing member 2 side) from the collar upper surface 14a.

  The leg portions 15 are legs for fixing the light beam control member 4 at a predetermined position and fixing the height, and are formed on the bottom surface 14c of the flange portion at equal intervals. The leg 15 is bonded with an adhesive 16 (see FIG. 3B described later) in a state where the light flux controlling member 4 is positioned on the surface 17a of the substrate 17.

  Consider that the leg 15 is integrally formed of the same material on the light flux controlling member 4 and the leg 15 is fixed to the substrate 17.

  When the light flux controlling member 4 is attached to the substrate 17, a gap ε is formed between the light emitting surface of the light emitting element 3 and the back surface 12 of the light flux controlling member 4. There are various reasons for forming the gap ε, but in a state where the light flux controlling member 4 is placed on the substrate 17 so that the light emitting element 3 is accommodated in the recess 13, heat generated from the light emitting element 3 is radiated by the gap ε. The purpose is given as an example.

  FIG. 3 is a diagram for explaining the influence when the leg portion 15 of the light flux controlling member 4 is bonded to the surface 17a of the substrate 17, and FIG. 3A is a plan view of the light flux controlling member 4 as viewed from above. 3 (b) is an enlarged view of the leg 15 of FIG. 3 (a).

  As shown in FIG. 3A, three leg portions 15 are formed at equal intervals on the flange lower surface 14c (see FIG. 2), and an adhesive 16 is formed on the surface 17a of the substrate 17 (see FIG. 3B). Is adhered by.

  The adhesive 16 is made of a thermosetting resin or the like, and the legs 15 are fixed on the substrate 17 by curing the resin with heat. In this application, a black one is known as a thermosetting adhesive that is cured at a predetermined temperature to obtain a sufficient adhesive strength.

JP 2007-59489 A JP 2006-92983 A

  However, the lens body disclosed in Patent Document 1 has a high cost because the lens portion and the alignment portion are formed of different materials.

  Further, when the leg portion 15 is formed on the flange portion 14 of the light flux controlling member 4 disclosed in Patent Document 2 and mounted on the substrate 17 with the black adhesive 16, the light is absorbed by the portion of the adhesive 16, and the light flux The display surface of the control member 4 may be affected. As shown in FIG. 3A, when viewed from above, the position of the leg 15 is reflected in the light diffusing member 2 (FIG. 2), and the luminance uniformity is uneven. As shown in FIG. 2, when many light flux control members 4 are arranged, a thin dark line appears on the light diffusing member 2 (FIG. 2) due to the uneven brightness uniformity. The unevenness in luminance uniformity hinders uniform surface illumination and degrades the illumination quality.

  The present invention has been made in view of such points, and the light beam control portion and the alignment portion (leg portion) are integrally formed, and the leg portion is attached to the substrate using an adhesive having a characteristic of absorbing light. An object of the present invention is to provide a light flux controlling member, a light emitting device, a surface light source device, and a display device capable of obtaining an irradiated surface with high luminance uniformity even when bonded.

  The light flux controlling member of the present invention includes a light control emission surface that controls the emission direction of light emitted from a light emitting element, a back surface that faces the light control emission surface and forms a bottom portion, and the light control emission from the back surface. A light beam control member having a leg portion formed so as to protrude toward the side opposite to the surface, wherein the leg portion is formed so that most of the formation region on the back surface is a light traveling at the center of the emitted light beam. When a light beam parallel to the reference optical axis as a direction is incident on the light beam control member as an incident light beam from the entire surface of the light control exit surface, the incident light beam that directly reaches the back surface from the light control exit surface does not exist The structure formed in the blind spot area is adopted.

The light emitting device of the present invention is arranged on a substrate, and emits light, a light control emitting surface that controls the emission direction of light emitted from the light emitting element, and the light control emitting surface, A light flux control member having a back surface forming a bottom portion and a leg portion installed on the back surface, wherein the leg portion is a perpendicular line extending from the arbitrary point of the outermost edge portion of the light control exit surface to the back surface. A configuration is adopted in which the distance is set within the range of the area width L given by the following equation inside the virtual circle on the back surface having a radius between the foot and the reference optical axis.
L = t × tan (α−β)
t: Distance from the foot of the perpendicular on the back surface of the outermost edge portion α: Angle of incidence of light parallel to the reference optical axis on the light control exit surface at the outermost edge portion β: On the reference optical axis The exit angle of the refracted light generated when parallel light enters the outermost edge from the light control exit surface

  The light emitting device of the present invention is arranged on a substrate, and emits light, a light control emitting surface that controls the emission direction of light emitted from the light emitting element, and the light control emitting surface, A light flux controlling member having a back surface forming a bottom portion, a substantially annular flange portion projecting radially outward of the light control emission surface, and a leg portion installed on the back surface including the flange portion. And the flange portion has a concave groove on the light control emission surface facing the leg portion.

  The light emitting device of the present invention is arranged on a substrate, and emits light, a light control emitting surface that controls the emission direction of light emitted from the light emitting element, and the light control emitting surface, A light flux controlling member having a back surface forming a bottom portion, a substantially annular flange portion projecting radially outward of the light control emission surface, and a leg portion installed on the back surface including the flange portion. And the leg portion has a retroreflective structure that retroreflects light incident from the light control exit surface side.

  The surface light source device of the present invention employs a configuration including the light flux controlling member or the light emitting device, and a light diffusing member that diffuses and transmits light from the light emitting device.

  The display apparatus of this invention takes the structure provided with the said surface light source device and the to-be-illuminated member which irradiates the light from the said surface light source device.

  According to the present invention, when the light flux controlling member is mounted on the substrate, even if light is absorbed in the adhesive portion, the legs and the adhesive installed in the ring-shaped area having the area width L It is possible to prevent problems that do not appear from directly above the member and affect the display surface of the light flux controlling member, and it is possible to prevent the occurrence of uneven brightness uniformity due to leg adhesion. As a result, the illumination light of the light flux controlling member can be made uniform, and high quality illumination quality can be obtained.

Plan view of a surface light source device constituting a conventional display device Sectional drawing of the display apparatus cut | disconnected and shown along the X1-X1 line | wire of FIG. The figure explaining the influence at the time of adhere | attaching the leg part of the conventional light beam control member on the surface of a board | substrate The figure which shows the detailed structure of the light beam control member of the surface light source device which comprises the display apparatus which concerns on Embodiment 1 of this invention. The figure explaining the area width L which is an attachment position of the leg part installed in the back surface of the light beam control member which concerns on the said Embodiment 1. FIG. The figure which shows typically the area | region of the area width L of the back surface of the light beam control member which concerns on the said Embodiment 1. FIG. The figure which shows the detailed structure of the other light beam control member of the surface light source device which comprises the display apparatus which concerns on the said Embodiment 1. FIG. The figure which shows the detailed structure of the light beam control member which concerns on Embodiment 2 of this invention. The figure which shows the state which looked at the shape of the V groove of the collar part of the light beam control member which concerns on the said Embodiment 2 from the cross section and upper surface of the collar part. The figure which shows the detailed structure of the light beam control member which concerns on Embodiment 3 of this invention. The figure which shows the state which looked at the shape of the retroreflection structure of the leg part of the light beam control member which concerns on the said Embodiment 3 from the cross section and the bottom face The figure explaining the effect | action of the retroreflection structure of the leg part of the light beam control member which concerns on the said Embodiment 3. FIG.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 4 is a diagram showing a detailed configuration of the light flux controlling member according to Embodiment 1 of the present invention. The light flux controlling member of the present embodiment can be applied to the surface light source device 1 and the liquid crystal display panel of FIG. The light flux controlling member 100 according to the present embodiment is used in place of the light flux controlling member 4 shown in FIGS. The reference optical axis refers to the traveling direction of light at the center of the three-dimensional outgoing light beam from the light beam control member 100. In the present embodiment, a case where the optical axis of the light emitting element 3 and the reference optical axis are coincident will be described as an example.

  The light flux controlling member 100 is a diffusing lens that controls the emission of light from the light emitting element 3, and is, for example, an aspherical lens. The light flux controlling member 100 is made of, for example, a transparent resin material such as PMMA (polymethyl methacrylate), PC (polycarbonate), EP (epoxy resin), or transparent glass.

  The light flux controlling member 100 includes a light control emitting surface 110 having a substantially circular planar shape for controlling the emission of light from the light emitting element 3 and a principal ray including light emitted from the light emitting element 3 in the reference optical axis direction. A recess 130 that enters the inside, and a back surface (bottom) 120 that extends in the radial direction from the opening edge of the recess 130 and that makes a sub-beam emitted from the light emitting element 3 at a large angle with respect to the reference optical axis enter the inside. A substantially annular flange 140 protruding outward in the radial direction of the light control exit surface 110, and a round bar-like leg installed within the area width L on the back surface 120 and in the vicinity of the flange 140 150. The upper surface 140a of the collar portion 140 (the light diffusing member side) is positioned facing the collar upper surface 140a, the outer surface of the collar portion 140 is opposed to the collar side surface 140b, and the collar upper surface 140a to form a part of the back surface 120. The surface is a collar lower surface 140c.

  The light control emission surface 110 protrudes upward (to the light diffusing member side) from the collar upper surface 140a. The light control exit surface 110 includes a first exit surface 110a located in a predetermined range centered on the optical axis L, a second exit surface 110b formed continuously around the first exit surface 110a, It consists of the 3rd output surface 110c which connects the 2nd output surface 110b and the collar upper surface 140a.

  The first emission surface 110a has a smooth curved surface shape that protrudes downward, and has a concave shape obtained by cutting a part of a sphere. The second emission surface 110b is formed in a continuous and convex curved surface shape that is continuous with the first emission surface 110a, and the planar shape surrounds the first emission surface 110a. Is formed. The third exit surface 110c is an inclined surface that is substantially linear in the cross section passing through the reference optical axis L. However, the second exit surface is not in a shape that prevents wide-range and uniform exit from the light flux controlling member 100. It may be a surface on a cross-sectional curve that is smoothly connected to 110b.

  The leg parts 150 are legs for fixing the light beam control member 100 at a predetermined position and fixing the height, and three legs 150 are formed on the back surface 120 at intervals. In the present embodiment, three are formed at equal distances and at equal intervals from the reference optical axis. The leg 150 is bonded with an adhesive (not shown) in a state where the light flux controlling member 100 is positioned on the surface of the substrate.

  When the light flux controlling member 100 is attached to the substrate, a gap ε is formed between the light emitting surface of the light emitting element 3 and the back surface 120 of the light flux controlling member 100. There are various reasons for forming the gap ε. For example, an attachment error when the light flux controlling member 100 is placed on the substrate so that the light emitting element 3 is accommodated in the recess 130, a purpose of radiating heat generated from the light emitting element 3, and the like. Is mentioned.

  The leg 150 is adhered to the surface of the substrate with an adhesive.

  As described above, the adhesive is made of a thermosetting resin and the like, and the resin is cured by heat to fix the leg 150 on the substrate. The thermosetting resin in this application is mostly colored such as black or dark brown at present.

[Formation position of leg 150]
There is a characteristic in the formation position of the leg part 150 installed in the back surface 120 of the light beam control member 100.

  The leg 150 is installed within the area width L of the back surface 120 of the light flux controlling member 100. In the area of the area width L, when a parallel light beam parallel to the reference optical axis is incident on the light beam control member 100 from the entire surface of the light control output surface 110, light is directly propagated from the light control output surface 110 toward the back surface 120. This is a blind spot area where the light does not reach the back surface 120 when it is exposed. This will be described in detail below.

  FIG. 5 is a diagram for explaining the area width L that is a position where the leg portion 150 installed on the back surface 120 of the light flux controlling member 100 in FIG. 4 is formed.

  As shown in FIG. 5, the third exit surface 110 c of the light control exit surface 110 of the light flux controlling member 100 intersects the flange 140 with an angle. Attention is now paid to the intersection of the third exit surface 110c and the collar 140. A tangent line 111 is drawn on the third exit surface 110c, and its normal line 112 is represented by a broken line. A light beam 113 parallel to the reference optical axis that is incident on the outermost edge 110d of the light control exit surface 110 from directly above the light beam control member 100 (on the light diffusion member side) is represented by a thick solid line. The angle formed between the tangent 111 of the third exit surface 110c and the reference optical axis is the lens tilt angle θ (equal to the angle formed between the tangent 111 and the light beam 113 parallel to the reference optical axis), and the light beam 113 is the outermost edge. An angle formed between the normal line 112 and the refracted light 115 generated by entering the light control exit surface 110 from 110d is defined as an exit angle β on the light control exit surface 110.

The light beam 113 is incident from the air (first medium: n _air ) to the transparent resin material or the like (second medium: n _pmma ) of the light flux controlling member 100 at an incident angle α. Therefore, a part of the incident light is refracted toward the reference optical axis of the light flux controlling member 100 on the incident surface. In other words, the incident light beam 113 is divided into light (straight light) 114 that travels straight in the same direction as the light beam 113 and light (refracted light) 115 that is refracted toward the reference optical axis of the light flux controlling member 100. The width at which the straight light 114 and the refracted light 115 reach the back surface 120 (see FIG. 4) of the light flux controlling member 100 is a blind spot area, which is an area width L.

The area width L is given by the following equation (2) when defining parameters according to the following equation (1). Here, n _pmma is the refractive index of the transparent resin material or the like of the light flux controlling member 100, and t is the thickness of the flange 140.

n _pmma sin β = n _air sin α
n _{pmma sin} β = 1.49
n _air = 1
β = sin ⁻¹ (sin α / 1.49)
... (1)
L = t × tan (90−β−θ)
θ = 90−α
L = t × tan (α−β) (2)
As shown in Expression (2), when the shape of the light flux controlling member 100 is determined, the area width L that is an appropriate range as the formation position of the leg 150 is determined.

  The flange 140 is not essential for the light flux controlling member 100. The value t when the flange 140 is not formed is a distance from an arbitrary point of the outermost edge portion 110d of the light control emission surface 110 to the foot of the perpendicular when the vertical line is lowered to the back surface 120.

  FIG. 6 is a diagram schematically showing an area having an area width L on the back surface 120 (see FIG. 4) of the light flux controlling member 100. FIG.

  As shown in FIG. 6A, the area of the area width L has a light flux controlling member due to the light control exit surface 110 and the collar 140 (see FIG. 4) of the light flux controlling member 100 being annular. It is distributed in a ring shape on the back surface 120 of 100.

  The leg 150 may be disposed at any position on the back surface 120 of the light flux controlling member 100 as long as it is within the area width L. The shape of the leg 150 is arbitrary, and the number thereof is not limited. For example, as shown in FIG. 6B, the leg 150 may have a circular leg 150a in cross section, and the leg 150 may have an elliptical arc shaped leg 150b. Although not shown in the drawings, an aspect in which one circular leg 150 is formed over the entire circumference within the range of the area width L, or an aspect in which a plurality of arc-shaped legs 150 are used as viewed from the center. But you can. In the present embodiment, from the viewpoint of easy work in the process of attaching the leg 150 to the substrate with an adhesive and improvement in stability after the leg 150 is attached, the three legs 150 having a round bar shape with a circular cross section are provided. used.

  Hereinafter, the operation of the light flux controlling member 100 configured as described above will be described.

  With reference to FIG. 4, the operation of light flux controlling member 100 having leg portions 150 within the range of area width L will be described.

  The light flux controlling member 100 is a diffusing lens that controls the emission of light from the light emitting element 3, and light that is incident from directly above the light flux controlling member 100 (light diffusing member side) is rarely considered.

  In the present embodiment, the leg 150 is prevented from being reflected on the light flux controlling member 100 when viewed from directly above the light flux controlling member 100 (on the light diffusing member side). Accordingly, attention is focused on light parallel to the reference optical axis that is incident from directly above the light flux controlling member 100.

  As shown in FIG. 4, the light parallel to the reference optical axis incident on the light control exit surface 110 and the collar 140 from directly above the light flux controlling member 100 is (1) the first exit surface 110a and the second exit surface. Near the center of the surface 110b, the light travels in the light flux controlling member 100 with almost no refraction, and reaches the back surface 120 or the recess 130. (2) Further, in the vicinity of the outer edge of the second light exit surface 110b and the third light exit surface 110c, the light travels in the light beam control member 100 in a state of being refracted in the center direction of the light beam control member 100, and from the back surface 120 to the outside Exit. The light incident from the third exit surface 110c and propagating through the light flux controlling member 100 is further refracted and emitted to the reference optical axis side on the back surface 120. Of the light incident on the first exit surface 110 a, the light incident on the recess 130 is scattered by the recess 130 in a state where the angles are scattered within the light flux controlling member 100. Since this area is not suitable as a formation position, this light is ignored. (3) The light parallel to the reference optical axis that has entered the collar 140 from directly above the light flux controlling member 100 propagates through the light flux controlling member 100 without being refracted and reaches the back surface 120.

  Eventually, the light parallel to the reference optical axis that has entered the light control exit surface 110 and the collar part 140 from directly above the light flux control member 100 propagates in the light flux control member 100 without being refracted in the collar part 140, and the back surface. On the other hand, on the third exit surface 110 c, the light travels in the light beam control member 100 while being refracted in the central direction of the light beam control member 100 and reaches the back surface 120. As a result, as shown in FIG. 4, a ring-shaped area having an area width L is formed on the back surface 120 of the light flux controlling member 100 so that light parallel to the reference optical axis incident from directly above the light flux controlling member 100 does not reach. Is done. The ring-shaped area having the area width L is an area that is hidden when viewed from directly above the light flux controlling member 100 (on the light diffusing member side) and is not directly visible.

  In the present embodiment, the leg 150 is installed at the position of the back surface 120 of the light flux controlling member 100 where the ring-shaped area is formed. The leg 150 is a leg for fixing the position and height of the light flux controlling member 100. Further, the leg 150 is positioned and bonded on the substrate with a colored adhesive.

  As described above, the back surface 120 position (ring-shaped area having an area width L) of the light flux controlling member 100 where the leg 150 is installed is an area that is not directly visible when viewed from directly above the light flux controlling member 100. Therefore, the leg 150 and the adhesive are not reflected. For this reason, when the light flux controlling member 100 is mounted on the substrate, it is possible to prevent a problem that light is absorbed by the adhesive portion and a dark portion is generated on the display surface of the light flux controlling member 100, and the leg portion is bonded. It is possible to prevent the occurrence of uneven brightness uniformity due to the above.

  As described above in detail, according to the present embodiment, the light flux controlling member 100 is a reference for a perpendicular foot drawn from the outermost edge portion 110d of the third exit surface 110c of the light control exit surface 110 to the back surface 120. A region having an area width L inside the virtual circle C on the back surface 120 having a radius from the optical axis as a radius, and a round bar-shaped leg 150 installed in the range, the area width L is It is given by the following formula.

L = t × tan (α−β)
t: the thickness of the flange 140 or the height of the outermost edge 110d from the back surface 120 α: the incident angle of the light 113 parallel to the reference optical axis on the light control exit surface 110 at the outermost edge 110d β: reference light The exit angle from the light control exit surface 110 of the refracted light 115 generated when the light 113 parallel to the axis enters the light control exit surface 110 from the outermost edge 110d.

  The ring-shaped area having the area width L is an area that is not directly visible when viewed from directly above the light flux controlling member 100, and the leg 150 is installed in this ring-shaped area. Therefore, when the light flux controlling member 100 is mounted on the substrate, even if light is absorbed by the adhesive portion, the legs 150 and the adhesive installed in this ring-shaped area are directly above the light flux controlling member 100. Therefore, it is possible to prevent a problem that affects the display surface of the light flux controlling member 100. At present, the adhesive made of thermosetting resin is only black or dark brown, but the light flux controlling member 100 can be mounted on the substrate using such an adhesive. Since an inexpensive thermosetting resin adhesive can be used without using a special adhesive, it can be carried out at a low cost and for general use. As a result, it is possible to prevent unevenness in luminance uniformity due to the adhesion of the leg portions, and to obtain high-quality illumination quality.

  Although the colored adhesive is a main cause of affecting the display surface of the light flux controlling member 100, it cannot be said that there is no influence of the reflection of the leg 150 itself. In the present embodiment, it is possible to mitigate the influence of reflection around the leg 150.

  Further, the leg 150 does not necessarily have to be entirely within the range of the area width L.

  FIG. 7 is a diagram showing a detailed configuration of another light flux controlling member of the surface light source device constituting the display device according to the first embodiment, and the same components as those in FIG. Description of the location is omitted.

  As shown in FIG. 7, even if a part of the leg 150 is formed so as to protrude outside the area width L, the leg area width L with respect to the light emitting area of the surface light source device using the light flux controlling member. If the amount of protrusion (area) from the light source is small, the dark part is hardly recognized from the light emitting surface, and high quality illumination quality can be obtained.

(Embodiment 2)
FIG. 8 is a diagram showing a detailed configuration of the light flux controlling member according to the second embodiment of the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals, and description of overlapping portions is omitted. The light flux controlling member 200 according to the present embodiment is used in place of the light flux controlling member 4 shown in FIGS.

  The light flux controlling member 200 is a diffusing lens that controls the emission of light from the light emitting element 3, and is, for example, an aspherical lens. The light beam control member 200 has the same configuration as the light beam control member 100 of FIG.

  The light flux controlling member 200 has a light control emitting surface 110 having a substantially circular planar shape for controlling the emission of light from the light emitting element 3 and a principal ray including light emitted from the light emitting element 3 in the reference optical axis direction. A recess 130 that is incident on the inside, a back surface 120 that extends in a radial direction from the opening edge of the recess 130, and that makes a sub-beam emitted from the light emitting element 3 at a large angle with respect to the reference optical axis, and an upper surface It has a concave V-shaped groove 240a (on the light diffusing member side), a substantially annular flange 240 protruding outward in the radial direction of the light control exit surface 110, and the back surface 120 and faces the V-shaped groove 240a. And a round bar-like leg portion 250 installed at the position.

  The collar portion 240 includes a concave V-shaped groove 240a on the upper surface (light diffusion member side) facing the leg 250 formation position on the back surface (substrate side). The V groove 240a may be a concave depression, and typically has a pyramid shape such as a cone, a quadrangular pyramid, or a triangular pyramid. In FIG. 8, a quadrangular pyramid-shaped V groove 240 a is formed on the upper surface of the collar portion 240. In addition, the angle of the inclined surface of the V groove 240a is set to an inclination angle at which the light incident from directly above the light flux controlling member 200 does not reach the leg 250 formation position in consideration of the wall thickness t of the flange portion 240.

  The legs 250 are legs for fixing the predetermined position of the light flux controlling member 200 and fixing the height, and three legs 250 are formed at equal intervals on the concentric circumference of the inner peripheral surface of the collar 240. Here, a concave V-shaped groove 240a is formed on the upper surface (light diffusing member side) of the flange portion 240 facing the position where the leg portion 250 is formed. The leg portion 250 is bonded with an adhesive in a state where the light flux controlling member 200 is positioned on the surface of the substrate.

  FIG. 9 is a diagram illustrating the shape of the V groove 240a of the flange portion 240 as viewed from the cross section and the top surface of the flange portion 240. FIG. As shown in FIGS. 9A, 9B, and 9C, the V-groove 240a of the collar portion 240 may form any one of a cone, a square weight, or a triangular pyramid. In the case of a weight having a ridge line such as a square weight or a triangular pyramid, the direction of the ridge line of the weight is arbitrary. Also, a V-groove structure that is not a weight may be used.

  Hereinafter, the operation of the light flux controlling member 200 configured as described above will be described.

  Similar to the first embodiment, the present embodiment prevents the leg portion 250 from being reflected in the light beam control member 200 when viewed from directly above the light beam control member 200 (on the light diffusion member side). .

  As shown in FIG. 8, the light incident on the collar 240 from directly above the light flux controlling member 200 (on the light diffusing member side) is refracted in a direction avoiding the center line of the leg 250 by the V groove 240a of the collar 240. Then, the light propagates through the light flux controlling member 200 and exits from the back surface 120 to the outside. The light refracted by the V-groove 240a and propagated in the light flux controlling member 200 is further refracted and emitted on the back surface 120 in a direction avoiding the center line of the leg portion 250.

  Thereby, in the leg part 250 formed just under the V groove 240a of the collar part 240, the area where the light parallel to the reference | standard optical axis which entered from right above the light beam control member 200 does not radiate | emit outside is formed. This area is an area that is concealed when viewed from directly above the light flux controlling member 200 (on the light diffusing member side) and is not directly visible, and is therefore a place where the leg portion 250 and the adhesive are not reflected. For this reason, when the light flux controlling member 200 is mounted on the substrate, the light is absorbed in the adhesive portion, and a problem that affects the display surface of the light flux controlling member 200 can be prevented. The occurrence of uneven brightness uniformity can be prevented.

  In the present embodiment, the leg portion 250 is made invisible directly by forming the V groove 240a in the flange portion 240. For this reason, it is only necessary to form an appropriate V-groove 240a in the collar portion 240, and the degree of freedom of the position where the leg portion 250 is formed can be improved. In particular, in Embodiment 1, the position of the leg 150 (see FIG. 4) is limited near the end of the third exit surface 110c of the light control exit surface 110, whereas this embodiment Then, it is only necessary to form the V-groove 240a on the upper surface of the flange portion 240 where the leg portion 250 is to be formed, and the degree of freedom of the leg portion 250 formation position can be improved. For the same reason, the shape of the collar portion 240 is not limited to a substantially annular shape protruding outward in the radial direction of the light control emission surface 110. For example, it may be a shape in which only the portion forming the V-groove is projected, and the leg portion 250 can be provided at a position facing the protruding portion. Thus, the light flux controlling member 200 can expand versatility when mounted on the substrate.

(Embodiment 3)
FIG. 10 is a diagram showing a detailed configuration of the light flux controlling member according to Embodiment 3 of the present invention. The same components as those in FIG. 4 are denoted by the same reference numerals, and description of overlapping portions is omitted. The light flux controlling member 300 according to the present embodiment is used in place of the light flux controlling member 4 shown in FIGS.

  The light flux controlling member 300 is a diffusing lens that controls the emission of light from the light emitting element 3, and is, for example, an aspheric lens. The light beam control member 300 has the same configuration as the light beam control member 100 of FIG.

  The light flux controlling member 300 has a light control emitting surface 110 having a substantially circular planar shape for controlling the emission of light from the light emitting element 3 and a chief ray including light emitted from the light emitting element 3 in the reference optical axis direction. A recess 130 that is incident on the inside, a back surface 120 that extends in a radial direction from the opening edge of the recess 130, and that allows a sub-beam emitted from the light emitting element 3 to enter the interior at a large angle with respect to the reference optical axis; A substantially annular flange 140 protruding outward in the radial direction of the control exit surface 110 and a round bar-shaped leg 350 having a retroreflective structure 350a inside the hollow are provided.

  The legs 350 are legs for fixing the predetermined position of the light flux controlling member 300 and fixing the height thereof, and three legs 350 are formed at equal intervals on the concentric circumference of the inner peripheral surface of the collar 140. The legs 350 are bonded by the adhesive 16 in a state where the light flux controlling member 300 is positioned on the surface of the substrate 17.

  The leg 350 includes a weight-shaped retroreflective structure 350a that protrudes downward (from the substrate side) from the back surface 120, and a cylindrical hollow leg 350b that surrounds the outer periphery of the retroreflective structure 350a.

  The retroreflective structure 350a may be a convex weight structure, and has a weight shape such as a cone, a square weight, or a triangular pyramid. In FIG. 10, a square pyramid-shaped retroreflective structure 350a is formed inside a hollow leg 350b. Further, the angle of the inclined surface of the retroreflective structure 350a is set to an angle at which light incident from directly above the light flux controlling member 300 is reflected and retroreflected by the retroreflective structure 350a. The retroreflective structure 350a can be retroreflected without processing such as coating.

  FIG. 11 is a diagram illustrating the shape of the retroreflective structure 350a of the leg portion 350 as viewed from the cross section and the bottom surface. As shown in FIGS. 11A, 11B, and 11C, the retroreflective structure 350a of the leg 350 may form any one of a cone, a quadrangular pyramid, or a triangular pyramid. In the case of a weight having a ridge line such as a square weight or a triangular pyramid, the direction of the ridge line of the weight is arbitrary. Further, a V-shaped protrusion structure which is not a weight may be used.

  FIG. 12 is a diagram for explaining the operation of the retroreflective structure 350 a of the leg 350. As shown in FIG. 12, the retroreflective structure 350a is a structure in which incident light is retroreflected by the weight surface and emitted. For example, in the case of a conical surface with a vertex angle of 90 °, the light parallel to the reference optical axis L is θr = 45 ° (which constitutes the leg portion 350) whose incident angle to the conical surface is larger than the critical angle. When the material is PMMA, the critical angle is about 42 °) and the light is totally reflected.

  The reason why the retroreflective structure 350a is formed shorter than the hollow legs 350b is as follows.

  That is, the adhesive 16 for fixing the leg portion 350 to the substrate 17 slightly wraps around the inside of the hollow leg portion 350 b to bond the hollow leg portion 350 b and the substrate 17. Therefore, the height dimension h2 of the retroreflective structure 350a is smaller than the height dimension h1 of the hollow leg 350b so that the top of the retroreflective structure 350a does not contact the wraparound adhesive. Is formed.

  Further, the height of the retroreflective structure 350a is higher than the height dimension h1 of the hollow leg 350b so that the top of the retroreflective structure 350a does not contact the adhesive 16 for fixing the leg 350 to the substrate 17. It is devised so that the dimension h2 becomes small.

  Hereinafter, the operation of the light flux controlling member 300 configured as described above will be described.

  In the present embodiment, similar to the first and second embodiments, the adhesive 16 for fixing the leg portion 350 to the substrate 17 is a light beam when viewed from directly above the light beam control member 300 (on the light diffusion member side). This prevents the control member 200 from being reflected.

  As shown in FIG. 11, the light that has entered the collar 140 from directly above the light flux controlling member 300 (on the light diffusing member side) propagates through the light flux controlling member 300 without being refracted, and exits from the back surface 120 to the outside. . Here, in the leg portion 350 formed on the back surface 120, the light incident from directly above the light flux controlling member 300 is retroreflected by the retroreflective structure 350a formed inside the leg portion 350, and again, the light flux controlling member 300. Return inside. The retroreflected light propagates again in the light flux control member 300 and is emitted to the outside from the flange 140 of the light flux control member 300.

  Thereby, in the leg part 350 which has the retroreflection structure 350a, the light which injected from right above the light beam control member 200 is substantially totally reflected, and is radiate | emitted from the original incident side.

  Thus, the leg part 350 retroreflects the light which reached | attained the leg part 350 to an incident side by providing the retroreflection structure 350a. For this reason, when the leg part 350 is adhered to the substrate 17 (see FIG. 10) with the adhesive 16 (see FIG. 10), the light propagated to the leg part 350 is incident even if the part of the adhesive 16 is a dark part. Since it is retroreflected to the side, the portion of the adhesive 16 is not visible from directly above the light flux controlling member 300, and it is possible to prevent a problem that affects the display surface of the light flux controlling member 300.

  In particular, in the present embodiment, the leg 350 itself provided with the retroreflective structure 350a is configured to minimize the directly visible area of the leg 350 and the adhesive 16 area. Therefore, there is a specific effect that the leg portion 350 can be installed at any position. The degree of freedom of the position where the leg 350 is formed can be further improved, and versatility when mounting the light flux controlling member 300 on the substrate can be expanded.

  The above description is an illustration of a preferred embodiment of the present invention, and the scope of the present invention is not limited to this.

  For example, the light diffusing member may be attached to the surface of the illuminated member on the light emitting element side, or in a state separated from the illuminated member, disposed on the surface of the illuminated member facing the light emitting element. You may do it.

  The light flux controlling member may be formed with a textured surface on the light control exit surface to diffuse light emitted from the light control exit surface.

  The light flux controlling member may be formed of a material containing a small amount of a light diffusing substance (for example, silicone particles or titanium oxide).

  In the above embodiments, the names of the light flux controlling member, the light emitting device, the surface light source device, and the display device are used. However, this is for convenience of explanation, and may be a flat light source, a display element, or the like. The light flux controlling member may be referred to as an LED diffusing lens.

  The light flux controlling member, the light emitting device, the surface light source device, and the display device according to the present invention can be widely used in applications such as a backlight of a monitor of a television monitor or a personal computer, an indoor indicator light, and various illuminations.

DESCRIPTION OF SYMBOLS 1 Surface light source device 2 Light diffusing member 3 Light emitting element 16 Adhesive 17 Substrate 100, 200, 300 Light flux controlling member 110 Light control emitting surface 110a First emitting surface 110b Second emitting surface 110c Third emitting surface 110d Outermost edge Part 120 back surface 130 dent 140 collar part 140a collar part upper surface 140b collar part side surface 140c collar part lower surface 150, 250, 350 leg part 240a V groove 350a retroreflective structure 350b hollow leg part

Claims (11)

A light control emission surface that controls the emission direction of the light emitted from the light emitting element, a back surface that faces the light control emission surface and forms a bottom portion, and from the back surface toward the opposite side of the light control emission surface A light flux controlling member having leg portions formed so as to protrude,
In the leg portion, a light beam parallel to a reference optical axis, which is a traveling direction of light at the center of the emitted light beam, is incident on the light beam control member as an incident light beam from the entire light control emitting surface. When formed, in the blind spot area where the incident light flux that directly reaches the back surface from the light control exit surface does not exist,
Luminous flux control member. A light emitting device arranged on a substrate and emitting light;
A light flux controlling member having a light control emitting surface for controlling the emitting direction of light emitted from the light emitting element, a back surface facing the light control emitting surface and forming a bottom portion, and a leg portion installed on the back surface. And
The leg portion is formed on the inner side of a virtual circle on the back surface having a radius of a distance between a leg of the perpendicular line drawn from the arbitrary point of the outermost edge portion of the light control exit surface and the reference optical axis, and the following formula A light-emitting device installed within the area width L given by
L = t × tan (α−β)
t: Distance from the foot of the perpendicular on the back surface of the outermost edge portion α: Angle of incidence of light parallel to the reference optical axis on the light control exit surface at the outermost edge portion β: On the reference optical axis The exit angle of the refracted light generated when parallel light enters the outermost edge from the light control exit surface A light emitting device arranged on a substrate and emitting light;
A light control emission surface that controls the emission direction of light emitted from the light emitting element, a back surface that faces the light control emission surface and forms a bottom portion, and protrudes radially outward of the light control emission surface. A light flux controlling member having a substantially annular collar and a leg installed on the back surface including the collar;
The said collar part is a light-emitting device provided with a concave-shaped groove | channel on the said light control output surface facing the said leg part. A light emitting device arranged on a substrate and emitting light;
A light control emission surface that controls the emission direction of light emitted from the light emitting element, a back surface that faces the light control emission surface and forms a bottom portion, and protrudes radially outward of the light control emission surface. A light flux controlling member having a substantially annular collar and a leg installed on the back surface including the collar;
The light emitting device includes a retroreflective structure in which the leg portion retroreflects light incident from the light control emission surface side.   The light-emitting device according to claim 3, wherein the groove has a concave cross section. The leg part is a retroreflective structure having a convex shape outward from the back surface;
The light-emitting device according to claim 4, further comprising a cylindrical leg surrounding the outer periphery of the retroreflective structure.   The light-emitting device according to claim 4, wherein the retroreflective structure has a convex cross-sectional shape of a weight.   The light emitting device according to claim 2, wherein the leg portion is integrally formed with a back surface of the light flux controlling member.   The light emitting device according to claim 2, wherein the leg portion is bonded onto the substrate via a colored adhesive. The light flux controlling member according to claim 1 or the light emitting device according to any one of claims 2 to 9, and a light diffusing member that diffuses and transmits light from the light emitting device,
A surface light source device comprising: The surface light source device according to claim 10, and a member to be illuminated that emits light from the surface light source device,
A display device comprising:

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